In a conventional apparatus for controlling conveyance between rollers, as described in Patent Literature 1, in order to convey a conveyed material between two rollers with applying stable and preset tension to the conveyed material, a speed controller for controlling a roller rotation speed for each roller is provided, and a speed command corresponding to a line speed is provided to each speed controller. Simultaneously therewith, tension of the conveyed material between the two rollers is detected by a tension control-amount detector, and an operation is made by a tension controller that executes PI (Proportional-Integrals control or PID (Proportional-Integral-Derivative) control so that a tension detection value matches a tension set value, thereby correcting the speed command with respect to a tension shaft, that is an axis of one of the two rollers based on an output of the tension controller.
In order that the apparatus for controlling conveyance between rollers; mentioned above stably conveys the conveyed material, tension control needs to be executed stably, and a gain of the tension controller needs to be set appropriately. In a typical apparatus for controlling conveyance between rollers, an operator observes tension fluctuation while performing conveyance between the rollers, and changes the control gain by trial and error. Therefore, there is a problem that a lot of labor or time is required for adjustment, and further, performance of stability differs depending on the level of skill of the operator.
Regarding this problem, in a technique described in Patent Literature 1, a model identification unit is provided to identify a control object model of a tension control system. An optimum value of a control gain is found using a genetic algorithm while repeating simulation and evaluation of responses at the time of changing the control gain to a candidate value using the control object model, thereby automatically performing adjustment of the control gain of a tension-control calculation unit.